There has been a method of calculating the amount of refrigerant in a split refrigerating and air-conditioning apparatus which includes an outdoor unit, serving as a heat source unit, and an indoor unit, serving as a use side, connected through refrigerant extension pipes, the method including performing operations for determining the volumes of the refrigerant extension pipes (two operations with different densities in the refrigerant extension pipe during cooling), dividing an increase or decrease in refrigerant in parts other than the refrigerant extension pipes between two operation states by a change in density of the refrigerant in the extension pipes to obtain the volumes of the refrigerant extension pipes, and calculating the refrigerant amount (refer to Patent Literature 1, for example).